1. Field of the Invention
The present invention relates to an organic EL device using a polymer material as an organic EL light-emitting material, and to an efficient method of manufacturing the same.
2. Description of the Related Art
An organic EL device is a solid spontaneous light-emitting device which can be driven by a low voltage as compared with an inorganic EL element, and as compared with a conventional inorganic LED, it can be produced without a complicated growth process. Considering applications to portable displays, especially in comparison with a liquid crystal display (LCD), products with displays using an organic EL device does not require a backlight since light is emitted spontaneously, is lightweight and can be produced at low cost. The products with displays using an organic EL device have advantages such as a fast response and invulnerable to shocks due to the use of all solid state components. Organic EL devices are also expected to find application in flat panel displays.
The EL light-emitting material used for an organic EL device may be a monomer material or a polymer material. In general, a monomer material film is formed by vacuum deposition and a polymer material film is formed by a coating method. Forming the polymer material film does not require an expensive apparatus and is practical.
However, in the case of a full color display, if a polymer material is used as the EL light-emitting material, there is a problem in that it is difficult to form pixels by finely coating different EL light-emitting materials having light emission properties in the three primary colors, blue (B), green (G) and red (R). In the related art, different polymer materials were generally coated and distinguished by vacuum vapor deposition using a metal mask, but in this case, there is a limit to the machining dimensions of the metal mask. Further, it is difficult to increase the alignment precision of the mask. As a result, the resolution of the coated material could not be increased, and the device was also costly.
As another means of finely coating each of the polymers with different light emissions in the three primary colors, blue (B), green (G) and red (R), to form pixels, the inkjet method has also been considered. In this case, the polymer material can be used efficiently (there is little waste), and a higher definition pixel pattern can be formed than with a metal mask.
However, if the polymer was coated by the inkjet method, the polymer material used as the EL light-emitting material had to be injected in the form of an inkjet ink from a nozzle head into gaps formed by partitions of an insulating bank between a positive electrode and a negative electrode. As opening of the gap was small, the inkjet ink could not be supplied to a predetermined gap with reliability. This led to the problems such as color blur, or short-circuits between the positive electrode and negative electrode.
Accordingly, an object of the present invention is to provide an organic EL device which has a plurality of highly fine pixels, does not have problems such as color blur or short-circuiting between positive and negative electrodes, allows enlargement of the substrate easily, does not require a large vacuum device etc., does not require mask alignment, can utilize a material highly efficiently, is easily mass-produced, is high quality and can be suitably used as display or the like. Another object of the present invention is to provide an efficient method of manufacturing the organic EL device.